In a hard disk drive each magnetic recording data storage disk surface has an associated slider. The slider has a side that faces the disk that includes an air-bearing surface (ABS), and a back or trailing side that supports the patterned read/write head. In operation of the disk drive, the disks are rotated and the sliders are supported with their ABS very close to the disk surfaces. Because of the extremely close proximity of the sliders and their associated disk surfaces, and the high stresses encountered when the sliders are brought into contact or removed from contact with the disk surfaces, it is advantageous that the sliders have blended or rounded edges at their disk sides.
The sliders are built in wafer form, in which a large number of magnetic read/write heads are formed using semiconductor processing techniques on the surface of a ceramic wafer. Typically up to 20,000 heads can be patterned on a 5-inch diameter wafer. The wafer is formed of a ceramic composite material containing TiC and Al2O3, as well as trace amounts of other materials, such as MgO. After the read/write heads are patterned, the wafer is cut into blocks called “quads”, the quads are cut into rows, and the rows are cut into sliders. Each of these cutting processes is typically performed with a diamond-tipped saw. Once the wafer rows have been cut from the wafer, the individual sliders can be partially cut with a saw and then later completely separated by a mechanical snapping or cleaving process. The sawing process, including the partial cutting process of the sliders in the wafer row, is described in detail in IBM's U.S. Pat. No. 5,739,048, which is incorporated herein by reference. In that patent, FIG. 1A shows a wafer with the patterned read/write heads, FIG. 2A shows a wafer row, and FIGS. 8-9 show a wafer row with partially separated sliders.
There are many disadvantages to the sawing process. The manufacturing cost of the sawing process is affected by several physical limitations. The size of the saw blade and therefore the size of the kerf area that is eradicated by the saw determines the spacing density of the sliders on a wafer. If the size of the saw kerf can be reduced, the sliders can be formed closer together and thus more sliders contained on a wafer, thereby reducing the per-slider cost. The sawing process with its associated large mechanical and frictional forces tearing into the slider material also produces a variety of physical damage, such as chipping, scratching, and cracking of the sliders and delamination of the patterned layers of the read/write heads. Because the sawing process includes significant rubbing it can also cause the accumulation of static electrical charge, which can damage the read/write heads when discharged. Finally, the sawing process leaves sharp comers and edges so that a separate edge blending or rounding step must be performed.
What is needed is a method of cutting wafers into quads, quads into rows, and especially rows into sliders that produces a reduced kerf region to allow closer packing of sliders on a wafer, that reduces physical and electrical damage to the sliders and the read/write heads, and that leaves blended or rounded edges on the disk sides of the sliders.